Apparatus for pouring molten metal into molds



June 8, 1965 Filed Sept. 18.

M. TAMA ETAL 3,187,394

APPARATUS FOR POURING MOLTEN METAL INTO MOLDS 1961 I 5 Sheets-Sheet 1 INVHVTORS W15? 5. ,SJ /EAR/IM/V BY Mi/O 7244A June 8, 1965 M. TAMA ETAL 3,187,394

APPARATUS FOR POURING MOLTEN METAL INTO MOLD S" 5 Shets-Sheet 2 Filed Sept. 18, 19,61

INVENTOR. M15? 5 JflAiM/JA/ 6/0 ZZMA ATTORNEYS June 8, 1965 M. TAMA ETAL 3,187,394

APPARATUS FOR POURING MOLTEN METAL INTO MOLDS Filed Sept. 18. 1961 5 Sheets-Sheet 3 INV EN TOR. 150? E. 56 549114 BY M45670 AYVOHNEV? June 8, 1965 M. TAMA ETAL 3,137,394

APPARATUS FOR POUEING MOLTEN METAL INTO MOLDS Filed Sept. 18. 1961 5 Sheets-Sheet 4 \IIIIIII 4 v1 II IIIIIIIII INVEN TOR.

' AizmkNm s June 8, 1965 M. TAMA ETAL 3,187,394

APPARATUS FOR POURING MOLTEN METAL INTO MOLDS Filed Sept. 18. 1961 5 Sheets-Sheet 5 I INVENTOR. M/ABMQ 5 SA 'AAM/W MAR/0 EMA AITGRNEYS' mamas 3,187,394 APPARATUS FGR PUURTNG MGLTEN METAL INTO MLD Mario Tania and Wilbur E. Shearmm, both of Morrisville, Pa, assignors to Atari Magnethermic Corperation, Youngstown, Ghio, a corporation cf Ghio Filed Sept. 18, 1961, Ser. No. 158,802 Claims. (Cl. 22-79) Gur invention relates to the artof supplying molten metal from a molten metal container to a mold and relates more particularly to methods and apparatus for repeatedly intermittently dispensing predetermined amounts of molten metals into molds, from a container holding a mass of molten metal.

In the mass production of castings, it is desirable to deliver repeatedly accurate amounts of metal, free. from slag or oxides, to molds at a proper temperature in relatively brief periods of time. It is important in casting,

that the quantity of metal poured be so controlled that a predetermined amount may be delivered at all times and that the quantity may be varied as required to dispense ditferent amounts without resort to complicated mech: anism for different size castings.

In the prior art, various methods of supplying molten metal from a holding furnace to a mold have beenused. Primarily manual ladling has been employed and in a ladling operation the melt which is to be hand ladled normally must be heated to a temperature above the desired casting temperature because of the exposure of the metal to cooling from the first to the last pour of the melt and hence in such method of dispensing the molten metal variations in the poured metal temperature occur and undesirable metal characteristics result as a consequence of the necessary overheating. Furthermore, safety hazardsare encountered due to spillage and loss of material during the transfer of the metal to the mold by the hand ladling. Fatigue of the operator is a further disadvantage. To overcome the necessity of hand ladling therefore, proposals have been made, as in US. Letters Patent No. 2,674,640 to provide apparatus in which hand ladling is eliminated and the melt is openly pumped into the molt, the metal being discharged through an inclined pouringtube externally of the molding container in predetermined amounts and describing, in some instances, a parabolic curve, dropping into the mold.

When the open pouring arrangement referred to above is resorted to, itohas been found important to hold the temperature of the metal at the overflow point of the pouring close to the temperature of the molten metal level in the holding container and a projection or extension of the main hearth is preferably provided to convey the The present invention has particular application in providing an improved pouring arrangement for pouring high temperature molten metals from metal melting or holding furnaces wherein the necessity of additional heating means for the metal within the pouring tube is eliminated.

The present invention moreover achieves a close coupling of the pouring tube with the molten bath wherefor the temperature of the molten bath and the temperature of the molten metal at the discharge end is maintained substantially the same during the entire pouring operation.

It is an object of the present invention to obviate the disadvantages of the prior art and to provide for the discharge of high temperature molten metals in accurate predetermined amounts at uniform temperature and at uniform discharge timeintervals for the same quantity. Generally speaking, a furnace for a high temperature molten metal bath is provided herein pressurized preferably by a low pressureair or gas dispensed in the space' above the metal level in the furnace to force molten metal up through improved discharge means into molds disposed successively in predetermined spaced relation adjacent thereto, the amountpoured into each mold being governed by the length of time a predetermined pressure is applied tothe surface of the melt.' Hence, a wide range of weights is possible simply by means of the adjustment of timer means.

A further object of our invention is to achieve in a tiltable furnace, regardless of the amount of metal held in the furnace, a discharge of predetermined definite quantities of molten metal and delivery of said discharged discharge of said molten metal from the tiltable furnace. at low velocity to eliminate any splashing or spillage of,

the metal.

Since the accuracy of the pour depends on the uni formity of the pressure exerted on the bath, the time chosen and the molten metal level in the discharge means,

and as metal is discharged from the molten metal con-- tainer or holding furnace, the level of the molten metal therein drops and if no compensation were provided the pressure or timing Would require adjustment as the level In a preferred form, according to the present invention, the holding compartment illustrated is of a type adapted to be tilted, and in such form the tilt of the furnace provides the compensation for the differences in the level of the molten metal as the metal is discharged from the furnace While the pouringtime and pressure is held constant. The degree of the tilt of the holding compartment in the form shown herein is controlled by sensing means mounted either adjacent the extreme outward tip of molten metal in the pouring tube or in another form adjacent an equivalent point in the holding compartment to control the tilt of the furace so that, regardless of the level in the furnace, the relationship of pouring time and amount of pour will remain the same. Thus, a further object is to discharge predetermine amounts of molten metal from a tiltable furnace wherein Patented June s, 1965 the tilting of the furnace is automatically controlled by a sensing means responsive to the level of the molten metal in the discharge tube or, in another form, responsive to the level of the molten metal in the holding compartment of the furnace.

A still further object is to deliver a predetermined amount of molten metal in a substantially vertical relatively low velocity stream by providing a discharge chamber mounted on the furnace outwardly of the discharge tube, said discharge chamber having an exit orifice located remote from the outer end of said discharge tube.

Another form of our invention, shown herein, provides a method and apparatus of the type referred to wherein the holding compartment and pouring tube are adapted to move simultaneously with the movement of the conveyor carried molds so that the pouring follows the path of the conveyor movement.

Other objects of our invention and the invention itself will become more readily apparent by reference to the accompanying drawings, in which drawings:

FIG. 1 is a top plan view of a tiltable furnace embodying one form of the invention, certain parts being shown in dotted lines and the electrical circuitry of the sensing device of our invention being shown in dotted lines;

FIG. 2 is a sectional view of the furnace of FIG. 1 taken on the line 2-2 of FIG. 1;

FIG. 3 is an enlarged view taken on the line 33 of FIG. 1;

FIG. 4 is a view taken on the line 44 of FIG. 3;

FIG. 5 is a view taken on the line 55 of FIG. 1 showing the furnace of FIG. 1 in solid and dotted lines to indicate the tilt of the level of the metal in the furnace;

FIG. 6 is a top view of a turntable adapted to be employed with the furnace of FIGS. 1 through 5 inclusive;

FIG. 7 is a diagrammatic view of the axis of rotation of the discharge orifice and showing the common discharge pour point above a mold; and

FIG. 8 is a view of another form of the invention wherein the sensing device is mounted adjacent the metal holding container.

Referring now to the drawings, in all of which like parts are designated by like reference characters, it will be noted that in the first form of our invention illustrated in FIGS. 1 through 5 inclusive, the furnace shown is a titltable induction furnace 12, generally of the single chamber type as shown in US. Letters Patent to Mario Tama No. 2,937,789, which comprises a molten metal holding chamber 11 adapted to be heated by, for instance, an induction core and coil 13 that induces heat in channels 14, 15, 15, said holding chamber being being preferably provided with automatic temperature control mechanism (not shown in the figures of drawing). The holding chamber is provided with a cover 16 adapted to close the top 17 reasonably airtight by means of the gasket 18. Solenoid operated valves 19 and 20 are preferably used to apply pressure of air or gas directed through a conduit 21 to the furnace and the valves are operated by a timing device or timer (not shown in the figures of drawing).

The holding furnace, as illustrated, is provided with a discharge device, generally shown at 22 at one side of the furnace termed the forward side and a charging chamber 23 at an opposite side of the furnace termed the fill side. The holding chamber 11 preferably has sufficient capacity to allow operation for a reasonable time before recharging. The charging chamber 23 is provided with a cover or refractory door 24.

The holding chamber is, it will be noted, provided with an extension or pocket 25 and the upwardly inclined end of the cylindrical tube 26 is mounted in a generally funnel-shaped closure element 27 which is secured to the outer end of the extension or pocket of the holding chamber 11. A refractory lined cover 29' is preferably integrally secured to the refractory lined funnel-shaped closure 27 to form a generally enclosed pouring discharge chamber 29 and the said chamber is provided with a pour orifice 30 generally disposed adjacent the outwardly and forwardly disposed end of the furnace and disposed downwardly adjacent the outer edge thereof and positioned downwardly of the closure supported discharge end of the pouring tube. It will be noted that the lower discharge end of the chamber 29 is preferably generally funnel-shaped, being provided with arcuately tapered surfaces from the tube opening toward the orifice 30 and with inclined surfaces adjacent the orifice 30 on the forward and side faces of the chamber, to assist in the pour. The tube 26 is provided with a restricted orifice 28, similarly to the orifice shown in FIG. 3 of US. Letters Patent No. 2,674,640 to Tania, to provide throttle means for the molten metal discharged upwardly and outwardly through the tube 26 and the metal discharged from the tube 26 passes through the refractory lined container 29 and leaves said container through the orifice 30 disposed in a downwardly directed bottom wall thereof. If desired, a reducing flame may be employed, as shown in FIG. 2 at 36, to prevent freezing of the molten metal in the chamber 29 and prevent undesirable oxides from forming, and if desired, a reducing flame 37 may be disposed adjacent the flow point y to prevent the formation of oxides at this point. A suitable fiue means 33 is provided in the cover 29' to vent the reducing gas stream 36. It will be noted that the discharge point is positioned closely adjacent and above the molds 31, which are indicated as carried on a conveyor 32 successively passing the discharge point 30.

The arcuate, tapered slope between the discharge end of the tube and the orifice 30 has an appreciable slope so that the metal may be discharged expediently and since in the present invention a tiltable furnace is used and the furnace is tilted to compensate for the level drop, this slope gradually is increased, as shown.

The funnel and exit orifice arrangement in the present chamber 29 is thus of great value in arresting the velocity and dropping the pour vertically, with only minor variations, into the mold. The molten metal emanating from the upper end of discharge tube 26 during the pour is of such a velocity that the molten metal tends to build up in the chamber 29 above the exit orifice 30 due to the relatively restricted size of said orifice. The buildup results in a relatively lower velocity discharge stream in a substantially vertical discharge path that is more easily controllable. This produces a fast pour at the beginning and a gradually decreasing velocity of pour at the end of the pour, the velocity varying, as will be apparent, in relation to the pressure created from the buildup of molten metal in the chamber 29 above the orifice 30. The size of the exit orifice 30 can, it is contemplated, also be changed easily to adjust the discharge rate to suit the type of mold being poured by, for example, providing block type inert orifices of various sizes, as shown in FIG. 2, adapted to be inserted into the opening 30 at the outlet end of the refractory lined container 29.

It will further be noted that the throttle means 28 is located in the lower part of the tube that is immersed in the molten metal. The throttle means determines the rate of metal discharged through the tube 26. The tube 26 is preferably made of good refractory material, such as silicon nitride bonded silicon carbide, which is not subject to attack by the molten metal, either below or above the metal level line.

The furnace 12 is tiltable by tilting apparatus 40 that may be operated hydraulically about a pivot axis x-x. In FIG. 5, the furnace is shown in solid lines in its untilted position and in dot-dash lines in its completely tilted position.

In the structure shown, the refill door 24 is adapted, when opened, to deactivate the level control, which level control consists of a sensing device 50 which is so disposed as to sense the level in the form of FIGS. 1 to 6 within easiest the pouring tube 26 and in the form of FIGS to sense the level Within the furnace. In FIG. 1, it will be noted that a gamma ray device is shown consisting preferably ofa radioactive isotope 51, completely shielded except for a small beam directed through the lining of the closure 27, and that said device is mounted at one side of the furnace adjacent a side portion of the closure 27, and is directed across the area of the portion of the pouring tube at the extreme outward tip of the preselected heighth of the molten metal therein, as indicated at 52. Directly opposite the isotope 51 on the opposite side of the closure element 27 is a detector unit 53 mounted thereon which produces a signal in proportion to the amount of radia- 'tion falling upon or beamed to it. This signal, fed into a suitable electronic circuit, operates a relay 55 which in turn operates a solenoid operated hydraulic valve 56 that controls the tilting cylinder 40. I

The furnace tilting bearings 69, 61 are, it is to be noted, so angularly displaced as to the discharge point, that their axis xx coincides with a point y, FIG. 3, slightly below the exit orifice of the discharge box and-the axis of the exit orifice St) is preferably positioned radially upwardly from this point, approximately from the vertical toward the furnace, as shown in FIG. 3. At the start of a batch, the molten metal stream exits from the orifice 'at an angled slope of 10 away from the furnace, as shown at a in FIG. 7, and toward the middle of the batch it drops vertically and at the end, as shown at b, it exits at a 10 angle toward the furnace. From all positions the molten metal stream passes through the point y, FIGS. 3 and 7, which coincides with the tilt axis and the mold sprue 31 is located directly thereunder. The entire furnace pivots about this tilting axis.

The pouringtube 26 and the level control point 26', being part of the furnace, also move. Since the control point in our invention is relative only to the furnace body, the gamma ray device is mounted on the furnace body, "sensing the level in the fill tube and adjusting the tilt of the furnace.

In operation, for refilling, the furnace is tilted downwardly to its lowermost position, the door opened, the level control deactivated, either automatically or by manual means, and molten metal is then charged into the chamber.

When the refill door is closed, the level control is reactivated. The cylinder then is raisedautomatically, as described above, to tilt the furnace and raise the level of the liquid melt in the pouring tube. When the level of the molten metal in the tube is sufficiently high to shield the gamma ray emission, the cylinder stops its ascent and the unit is ready to pour. With a mold positioned under the exit orifice 3%, pressure is applied to the main hearth for a predetermined length of time causing the metal to rise in the pouring tube and to overflow into the mold. Since the level control, or sensing device, only operates when the level in the tube is low, the furnace position does not change during the pour since during the pour the molten metal completely shields the sensing device by intercepting the same.

At the end of the pour, the pressure is rapidly exhausted and the molten metal in the pouring tube seeks the level of the metal in the main hearth. Since the pour has exhau'sted a quantity of molten metal, the level of the metal in the main hearth and in the pouring tube is now relatively lower providing less shielding-of the gamma ray isotope tube. Hence, when the level is lowered sufficiently, the sensing device again activates the cylinder and raises the furnace until the shielding by the molten metal in the pouring tube is again sufficient to deactivate it; When making large pours this sequence will occur with almost every pour. With smaller pours, several may be made before compensation occurs. The sequence continues until the usable material inthe holding chamber approaches exhaustion. Then the chamber must be recharged and the sequence begins again.

In FIG. 6, a hydraulically or mechanically operated turntable '70 is shown which is provided to permit the furnace of FIG. 1 or 8 to be rotated about its vertical axis so that the pour from the metal container may follow the mold, if desired, where a continuously moving conveyor 71 is employed. When a mold 72 approaches the furnace and its sprue lines up with the exit orifice of the furnace, the furnace turntable will begin rotating at a speed synchronized with the conveyor and the pour may then be discharged into the mold within the limited amount of travel permitted by the turntable as, for example in the form shown, Within approximately 18 inches. The turntable 70 is rotated by hydraulic cylinder means 73, the operation of which is synchronized by appropriate control means, e.g. timing means (not shown) with the conveyor speed and the pour cycle. 7

At the end of the pour, the rotation is reversed and the furnace is returned by the turntable to its starting position ready for the next mold. In this form, the axis of rotation is preferably located at the center of the cylindrical furnace to achieve a minimum of agitation of the melt Surface. As illustrated, the rotary movement of the furnace is independent of the tilting motion of the same which provides the compensation for the level differences in the molten metal chamber and each motion will func tion as their controls provide withoutassistance or interference from the other.

It will be'understood that various mechanisms other than a turntable might be employed to permit a tilting furnace of the types described herein to follow the mold,

if desired.

In FIG. 8, a tiltable molten metal container and dispenser of the type shown in FIGS. 1 to 5 inclusive, is shown. However, in this form of the invention the sensing device 1%, of the type shown at 54), in FIG. 1, is dis posed adjacent a corner at the forwardly disposed side of the furnace in an axis zz substantially parallel to the tilting axis xx, which axis 'zz intersects the point 26' of the pouring tube and is mounted on a level equivalent to the level of the mounting of the sensing device level control in FIGS. 1 to 5. The small beam of gamma rays from the radioactive isotope 101, in this form, is beamed through the hearth chamber wall 1612, a level control point in the melt indicated at 103, the wall 104 to the detector 165, which by comparable electronic circuitry to that indicated in FIG. 1, signals a relay operating through a solenoid valve to cause the hydraulic cylinder to lift the furnace and raise the level of metal in the tube 26 for the purposes of the level control of our invention.

While we have described our invention in terms of the particularembodiments herein illustrated and described, it will be understood that devices other than the particular sensing devices herein shown could be used and that such devices, in the event of usage of furnaces which can be recharged without'interruption of pour, might be used to control the automatic tilting of the said furnace in both directions. The form described hereinbefore and shown in FIG. 8 could, it will be readily understood, be employed in such a furnace.

While we have disclosed our invention in connection with certain preferred embodiments herein illustrated and described, it will be apparent that numerous changes and departures may be made therein, as indicated hereinbefore, without, however, departing from the spirit of our invention or the scope of the appended claims.

What we claim is:

1. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side thereof, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the said hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive.

2. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side thereof, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tubes, a refractory lined chamber secured to the discharge means, said refractory lined chamber containing a discharge orifice, said discharge orifice being disposed outward of and lower than the upper end of the inclined tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive.

3. The combination of claim 2 wherein means are dis posed intermediate said discharge orifice and the upper end of the tube for increasing the velocity of the molten metal discharged from said tube under conditions of pressure application and which guides the discharged molten metal through the discharge orifice at a point remote from said tube.

4. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side thereof, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive, said sensing device being mounted on said furnace relatively remote from said inclined tube.

5. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side thereof, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive, said sensing device being disposed adjacent said furnace, said sensing device being responsive to a decrease in level of the molten metal in said furnace resulting from the application of pressure by said pressure applying means.

6. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side of said hearth, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube,

means acuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive, the axis of said sensing device being disposed in a horizontal plane which passes through a predetermined point in the upper end of said inclined tube.

7. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side of said hearth, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive, the plane of the longitudinal axis of said sensing device intersecting the plane of the axis of the said tilting means.

8. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side thereof, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive, the axis of said tilting means being in a vertical plane which at all degrees of tilt of said furnace passes through a predetermined flow point slightly below the bottom of said discharge orifice.

9. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side thereof, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive, said level sensing device comprising a gamma ray device for providing a source of gamma rays and a gamma ray detector associated with said gamma ray device, said gamma ray device and detector being responsive to variations in the level of molten metal from a preselected level.

10. In a tiltable furnace comprising a main hearth adapted to contain molten metal, fill means disposed at one side thereof and discharge means disposed at another side of said hearth, said discharge means being provided with an inclined tube having its lower end submerged in the molten metal and its upper end disposed above the level of the molten metal, means for intermittently applying pressure to the molten metal within the hearth to cause molten metal to discharge through said tube, a sensing device to sense the level of the metal in said tube, means actuated by said level sensing device to tilt the hearth to maintain the level of metal in said tube at a predetermined level while said intermittent pressure applying means are functionally inactive, oscillating means for oscillating said furnace, means to control said oscillating means whereby said furnace oscillates in timed sequence with the movornent of molds therebelow to dis pense molten metal into said molds.

References Cit ed by the Examiner UNITED STATES PATENTS Robertson et a1 22-79 Howlett et a1. 22-82 Black 2279 Mefiert 22-79 Woddburn 22 -79 XR V 10 FOREIGN PATENTS 882,085 2/ 43 France. 663,943 1/52 Great Britain. 803,343 10/58 Great Britain.

Examiners. 

1. IN A TILTABLE FURNACE COMPRISING A MAIN HEARTH ADAPTED TO CONTAIN MOLTEN METAL, FILL MEANS DISPOSED AT ONE SIDE THEREOF AND DISCHARGE MEANS DISPOSED AT ANOTHER SIDE THEREOF, SAID DISCHARGE MEANS BEING PROVIDED WITH AN INCLINED TUBE HAVING ITS LOWER END SUBMERGED IN THE MOLTEN METAL AND ITS UPPER END DISPOSED ABOVE THE LEVEL OF THE MOLTEN METAL, MEANS FOR INTERMITTENTLY APPLYING PRESSURE TO THE MOLTEN METAL WITHIN THE HEARTH TO CAUSE MOLTEN METAL TO DISCHARGE THROUGH SAID TUBE, A SENSING DEVICE TO SENSE THE LEVEL OF THE METAL IN SAID TUBE, MEANS ACTUATED BY SAID LEVEL SENSING DEVICE TO TILT THE SAID HEARTH TO MAINTAIN THE LEVEL OF METAL IN SAID TUBE AT A PRE- 